The proposed research will investigate effects of children born before a union on childbearing in that union. We base our hypotheses and analyses on three key values of children. (1) Children signal the partners' commitment to each other; children born before a union do not have the same meaning. (2) Children confer parental status, which continues to be a primary marker of adulthood in all societies and which links individuals to lineages and kin networks. Step-parenthood may not confer the same status or connections as biological parenthood. (3) A second child ensures that each child will have a sibling. Step- or half- siblings may not substitute for full siblings, or may do so only if they live together. We will investigate effects of pre-union children on union fertility in a gendered context. Because mothers are much more likely than fathers to bring coresident children to a new union and to maintain contact with and responsibility for nonresident children, and because biological parenthood may be more salient to women's identities than to men's, we expect women's children to have stronger effects on the couple's childbearing than men's children. We will analyze data from the U.S. National Survey of Families and Households (1988/1993 panel). We will use retrospective birth and union histories to estimate the parity-specific birth risks for unions and for individuals, contingent on children born before a particular union. These histories will also be used to estimate effects of pre-union children on unwanted or mistimed births in a union. For respondents in unions at the time of each survey, we will estimate effects of partners' pre-union and shared children on men's and women's childbearing intentions. Couple data will be used to estimate effects of partners' children on disagreement about future childbearing. Panel data will be used to analyze prospectively effects of partners' separate and shared children on a couple's birth risk, and to determine whether pre-union children moderate effects of partners' intentions on births. In each of these analyses, we will test (1) differences between effects of men's versus women's pre-union children; (2) differences between effects of older versus younger pre-union children; (3) differences in effects of children for whom parents have more or less childrearing responsibility (coresidence, contact, financial support); and (4) differences in effects of pre-union children on childbearing in marital versus cohabiting unions.